思澜二级公路改建工程石拱桥加固利用

公路改建工程主要依托老路进行,旧桥加固利用是公路改建工程中重要的环节,对降低工程造价、缩短施工周期、缓解施工中的保通压力有其现实意义,针对思澜公路石拱桥加固利用,对老石拱桥加固技术和经济效益进行探讨。     

Reinforcement Treatment on the Uneven Subsidence of Foundation

There are several methods to cope with the common problem of the uneven subsidence of foundation. The reason for uneven settlement of foundation of the frame structure was analyzed in this paper. Considering the limitation of the construction site and the principle of consolidation, a feasible reinforcement measure was taken. Meanwhile, a practical construction pattern was chosen upon the comparison of the reinforcement technology analysis and the construction method. The observation of the settlement result after consolidation of the structure shows that the result of this reinforcement treatment pattern is effective.     

Recommendations on Shrinkage and Temperature Reinforcements in Concrete Slabs

The mechanism of shrinkage cracking is discussed with a simple member, which is fully restrained and subjected only to an axial restraining force caused by shrinkage, while a simple procedure is presented for the determination of the number and spacing of the cracks and the average crack width. With the simple model, some examples are shown to compare the provisions for minimum shrinkage and temperature reinforcement in GB 50010-2002 Code, ACI 318-02 Code and AS 3600-1988 Code. The results show that the provisions in GB 50010-2002 Code are too weak in comparison with the others. Finally, some recommendations are proposed.     

加氢反应器接管补强部位的应力分析

以应力分析法和ANSYS有限元法分别对加氢反应器接管补强部位进行了应力分析,结果表明:最大应力出现在反应器上封头与接管的内壁交界处。通过分析得知,用ANSYS软件分析反应器接管补强部位的应力比传统应力分析法更直观方便,计算相对更精确省时。     

真空井点降水联合加固软土地基的施工技术分析

根据工程实际情况,应用真空井点降水联合加固软土地基的施工方法,通过施工沉降观测和理论分析,对真空井点降水联合预压加固软土地基的施工技术及加固有效深度、有效应力的变化问题进行了研究。验证了真空井点降水联合预压加固施工方法在寒区环境的适用性,分析了在该条件下,本施工方法的加固效果和沉降变化规律,为基础设计和工程施工提供参考依据。     

含植被坡体稳定性的年际变化规律研究

植被对边坡稳定的影响主要体现在2方面,一是植物地上部分的自重以及风荷载对坡面的压力;二是植物根系的固土作用.植物种类和生长期对含植被坡体土壤抗剪强度的影响随植物的生长发育过程而变化,且这种变化难以量化.本文通过构建单株植物模型,分析含有不同类型植被的浅层均质土坡安全系数的年际变化规律.结果表明,在综合考虑植被自重、风荷载和根系的影响条件下,含侧柏和荆条的坡体安全系数会随着植物的生长发育逐渐增大,分别在树龄为50年和30年左右达到峰值1.549和1.817,随后趋于稳定,二者的峰值安全系数较植被种植初期分别增加46.8％和54.9％.植被自重和风荷载减弱坡体的稳定性,其中植被自重影响相对较小,使含侧柏和荆条坡体的安全系数分别降低0.1％和0.7％,而风荷载的影响较为明显,使其安全系数分别降低5.9％和5.8％.研究结果可为正确评估坡体稳定性以及布设植物护坡措施提供一定的科学参考.     

Root tensile strength of three shrub species: Rosa canina, Cotoneaster dammeri and Juniperus horizontalis: Soil reinforcement estimation by laboratory tests

The presence of vegetation increases soil burden stability along slopes and therefore reduces soil erosion. The contribution of the vegetation is due to mechanical (reinforcing soil shear resistance) and hydrologic controls on stream banks and superficial landslides. This study focused on the biotechnical characteristics of the root system of three shrub species: Rosa canina (L.), Cotoneaster dammeri (C.K. Schneid) and Juniperus horizontalis (Moench). The aim of this paper is to increase our understanding on root biomechanical properties of shrubs species and their contribution to soil reinforcement. The considered shrubs grew up in wood containers, exposed to natural conditions in a village near Asti (Northern Italy) for 2 years. Laboratory tests were conducted to measure the ultimate root tensile strength and to estimate the root density distribution with depth (root area ratio), in order to quantify the soil mechanical reinforcement. Root tensile strength measurements were carried out on single root specimens and root area ratio was estimated analyzing the whole root system. The improvement of soil mechanical properties obtained by the presence of shrubs was estimated using two different models. The first model, based on a simple force equilibrium model, considers that the tensile strength of all roots crossing the shear plane is fully mobilized. This classical approach is implemented by the Fiber Bundle Model concept, to account for non-simultaneous root breaking. C. dammeri roots presented the highest tensile strength and soil reinforcement values, while R. canina and J. horizontalis were characterized by lower values. Similarly at each considered depth C. dammeri showed the highest soil reinforcement effect.